The present invention relates to a class of substituted amines, to pharmaceutical compositions containing them and to methods of treating neurological and neuropsychiatric disorders using such compounds.
Synaptic transmission is a complex form of intercellular communication that involves a considerable array of specialized structures in both the pre- and post-synaptic terminal and surrounding glial cells (Kanner and Schuldiner, CRC Critical Reviews in Biochemistry, 22, 1987:1032). Transporters sequester neurotransmitters from the synapse, thereby regulating the concentration of neurotransmitters in the synapse, as well as their duration therein, which together influence the magnitude of synaptic transmission. Further, by preventing the spread of neurotransmitter to neighbouring synapses, transporters maintain the fidelity of synaptic transmission. Lastly, by sequestering released neurotransmitter into the presynaptic terminal, transporters allow for neurotransmitter reutilization.
Neurotransmitter transport is dependent upon extracellular sodium and the voltage difference across the membrane. Under conditions of intense neuronal firing, for example, during a seizure, transporters can function in reverse, releasing neurotransmitter in a calcium-independent non-exocytotic manner (Attwell et al., Neuron, 11, 1993:401-407). Pharmacologic modulation of neurotransmitter transporters thus provides a means for modifying synaptic activity, which provides useful therapy for the treatment of neurological and psychiatric disturbances.
The amino acid glycine is a major neurotransmitter in the mammalian nervous system, functioning at both inhibitory and excitatory synapses. By nervous system, both the central and peripheral portions of the nervous system are intended. These distinct functions of glycine are mediated by two different types of receptor, each of which is associated with a different class of glycine transporter. The inhibitory actions of glycine are mediated by glycine receptors that are sensitive to the convulsant alkaloid strychnine, and are thus referred to as xe2x80x9cstrychnine-sensitivexe2x80x9d. Such receptors contain an intrinsic chloride channel that is opened upon binding of glycine to the receptor; by increasing chloride conductance, the threshold for firing of an action potential is increased. Strychnine-sensitive glycine receptors are found predominantly in the spinal cord and brainstem, and pharmacological agents that enhance the activation of such receptors will thus increase inhibitory neurotransmission in these regions.
Glycine also functions in excitatory transmission by modulating the actions of glutamate, the major excitatory neurotransmitter in the central nervous system (Johnson and Ascher, Nature, 325, 1987:529-531; Fletcher et al., Glycine Transmission, Otterson and Storm-Mathisen, eds., 1990:193-219). Specifically, glycine is thought to be an obligatory co-agonist at the class of glutamate receptor termed N-methyl-D-aspartate (NMDA) receptor. Activation of NMDA receptors increases sodium and calcium conductance, which depolarizes the neuron, thereby increasing the likelihood that it will fire an action potential.
NMDA receptors in the hippocampal region of the brain play an important role in a model of synaptic plasticity known as long-term potentiation (LTP), which is integral in certain types of learning and memory (Hebb, D. O (1949) The Organization of Behavior; Wiley, N Y; Bliss and Collingridge (1993) Nature 361: 31-39; Morris et al. (1986) Nature 319: 774-776). Enhanced expression of selected NMDA receptor sub-units in transgenic mice results in increased NMDA-receptor-mediated currents, enhanced LTP, and better performance in some tests of learning and memory (Tang et al. (1999) Nature 401: 63).
Conversely, decreased expression of selected NMDA receptor sub-units in transgenic mice produces behaviors similar to pharmacologically-induced animal models of schizophrenia, including increased locomotion, increased stereotypy, and deficits in social/sexual interactions (Mohn et al. (1999) Cell 98:427-436). These aberrant behaviors can be ameliorated using the antipsychotics haloperidol and clozapine.
NMDA receptors are widely distributed throughout the brain, with a particularly high density in the cerebral cortex and hippocampal formation.
Molecular cloning has revealed the existence of two classes of glycine transporters in mammalian brains, termed GlyT-1 and GlyT-2. GlyT-1 is found throughout the brain and spinal cord, and it has been suggested that its distribution corresponds to that of glutamatergic pathways and NMDA receptors (Smith, et al., Neuron, 8, 1992:927-935). Molecular cloning has further revealed the existence of four variants of GlyT-1, termed GlyT-1a, GlyT-1b, GlyT-1c and GlyT-1d. Two of these variants (1a and 1b) are found in rodents, each of which displays a unique distribution in the brain and peripheral tissues (Borowsky et al., Neuron, 10, 1993:851-863; Adams et al., i J. Neuroscience, 15, 1995:2524-2532). The third variant, 1c, has only been detected in human tissues (Kim, et al., Molecular Pharmacology, 45, 1994:608-617). The fourth variant has been detected in human tissues (see U.S. Pat. No.6,008,015). These variants arise by differential splicing and exon usage, and differ in their N-terminal regions. GlyT-2, is found predominantly in the brain stem and spinal cord, and its distribution corresponds closely to that of strychnine-sensitive glycine receptors (Liu et al., J. Biological Chemistry, 268, 1993:22802-22808; Jursky and Nelson, J. Neurochemistry, 64, 1995:1026-1033). Another distinguishing feature of glycine transport mediated by GlyT-2 is that it is not inhibited by sarcosine as is the case for glycine transport mediated by GlyT-1. These data are consistent with the view that, by regulating the synaptic levels of glycine, GlyT-1 and GlyT-2 selectively influence the activity of NMDA receptors and strychnine-sensitive glycine receptors, respectively.
Compounds which inhibit or activate glycine transporters would thus be expected to alter receptor function by modifying glycine concentrations in the synapse and, thus, provide therapeutic benefits in a variety of disease states.
For example, compounds which inhibit GlyT-1 mediated glycine transport may increase glycine concentrations at NMDA receptors, which receptors are located in the forebrain, among other locations. This concentration increase could perhaps elevate the activity of NMDA receptors, thereby possibly alleviating symptoms of schizophrenia and enhancing cognitive function. Alternatively, compounds that interact directly with the glycine receptor component of the NMDA receptor can have the same or similar effects as increasing or decreasing the availability of extracellular glycine caused by inhibiting or enhancing GlyT-1 activity, respectively. See, for example, Pitkxc3xa4nen et al., Eur. J. Pharmacol., 253,125-129 (1994); Thiels et al., Neuroscience, 46, 501-509 (1992); and Kretschmer and Schmidt, J. Neurosci., 16, 1561-1569 (1996).
It has been found that many compounds which are effective in binding to and inhibiting the GlyT-1 transporter, also display toxic effects when administered in vivo. While such compounds are useful pharmaceutical tools for studying the function of the transporters, toxicity would limit the usefulness of such compounds as pharmaceuticals.
Hence it is desirable to provide compounds that affect glycine transport. Also, it is desirable to provide compounds which affect glycine transport but which are sufficiently non-toxic so as to be useful in pharmaceutical compositions.
The present invention is directed to compounds which have been found to be effective in inhibiting GlyT-1 transport and are sufficiently non-toxic as to be medically useful. More particularly, the compounds of the invention show an unexpected improved toxicity profile over other known GlyT-1 inhibitors. According to one aspect of the invention, there are provided compounds of Formula I: 
wherein:
Ar1 is a thiophene group which may be 2 or 3 thiophene and is optionally substituted with up to one substituent selected from methyl or ethyl; and
Ar2 is selected from thiophene, furan and substituted phenyl, wherein the substituted on the phenyl group is selected from C1-6 alkyl, halo, C1-6 haloalkyl, C1-6 alkoxy, C1-6 haloalkoxy, cyano,
and a salt, solvate and hydrate thereof.
In Accordance with a further aspect of the invention there is provided the compound: (Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-methylphenyl)prop-1-en-3-yl)sarcosine.
It has been found that compounds of Formula I and the compound (Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-methylphenyl)prop-1-en-3-yl)sarcosine, inhibit glycine transport via GlyT-1, or are precursors (for example, pro-drugs) of such compounds. GlyT-1 transport inhibitors are useful in the treatment of schizophrenia, as well as other CNS-related disorders such as cognitive dysfunction, dementia (including that related to Alzheimer""s disease), attention deficit disorder, depression, and pervasive developmental disorders such as autistic disorder, Rett""s disorder, childhood disintegrative disorder, Asperger""s disorder and pervasive developmental disorders not otherwise specified (for example atypical autism).
According to another aspect of the invention there is provided a composition comprising a compound of formula 1 or the compound (z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-methylphenyl)prop-1-en-3-yl)sarcosine, and a carrier.
According to another aspect of the invention, there is provided a pharmaceutical composition comprising a compound of Formula I and a pharmaceutically acceptable carrier. In a further aspect of the invention there is provided a pharmaceutical composition comprising a compound of formula 1 in an amount effective to inhibit glycine transport, and a pharmaceutically acceptable carrier.
In a further aspect of the invention there is provided a pharmaceutical composition comprising the compound (Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-methylphenyl)prop-1-en-3-yl)sarcosine and a pharmaceutically aceptable carrier. In still a further aspect of the invention there is provided a pharmaceutical composition comprising the compound (Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-methylphenyl)prop-1-en-3-yl)sarcosine in a amount effective to inhibit glycine transport and a pharmaceutically acceptable carrier.
In another aspect of the invention, there are provided compositions containing compounds of Formula 1 or the compound (Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-methylphenyl)prop-1-en-3-yl)sarcosine in amounts suitable for pharmaceutical use to treat medical conditions for which a glycine transport inhibitor is indicated. Preferred are those compositions containing compounds useful in the treatment of medical conditions for which GlyT-1-mediated inhibition of glycine transport is needed, such as the treatment of schizophrenia or cognitive dysfunction.
The compounds of the Formula 1 or the compound (Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-methylphenyl)prop-1-en-3-yl)sarcosine can be used for treating a patient having a medical condition for which a glycine transport inhibitor is indicated, which indications are as recited above. A preferred indication is schizophrenia. The compounds can also be used for manufacturing a medicament for treating a patient having a medical condition for which a glycine transport inhibitor is indicated.
The term xe2x80x9calkylxe2x80x9d as used herein means straight- and branched-chain carbon and hydrogen containing radicals with 1, 2, 3, 4, 5 or 6 carbon atoms and includes methyl, ethyl and the like.
The term C1-6 as used herein means an alkyl radical of 1, 2, 3, 4, 5, or 6 carbon atoms.
The term xe2x80x9calkoxyxe2x80x9d as used herein means straight- and branched-chain alkyl groups terminating in an oxy radicals containing 1, 2, 3, 4, 5, or 6 carbon atoms and includes methoxy, ethoxy, t-butoxy and the like.
The term xe2x80x9chaloxe2x80x9d as used herein means halogen and includes fluoro, chloro, bromo and the like.
The term xe2x80x9chaloalkylxe2x80x9d refers to an alkyl group substituted by one or more independently selected halo atoms, such as xe2x80x94CF3.
Similarly, the term xe2x80x9chaloalkoxyxe2x80x9d refers to an alkoxy group substituted by one or more independently selected halo atoms, such as xe2x80x94OCF3.
Suitable embodiments of the invention include compounds of formula 1 wherein Ar1 is selected from optionally substituted 2-thiophene or 3-thiophene. In a suitable embodiment of the invention Ar1 is 2-thiophene. In a preferred embodiment of the invention Ar1, is 2-(3-alkylthiophene) preferably 2-(3-methylthiophene). In another preferred embodiment of the invention Ar1 is 3-thiophene. In a further preferred embodiment Ar1 is 3-(4-alkylthiophene), preferably 3-(4-methylthiophene).
In suitable embodiments of the invention Ar2 is selected from substituted phenyl, thiophene and furan. In a more preferred embodiment of the invention Ar2 is substituted phenyl wherein such substituents are at the 3, or 4 position, and wherein the substituents are selected from: C1-6 alkyl; halo; C1-6 haloalkyl; C1-6 alkoxy; C1-6 haloalkoxy; and cyano. In other preferred embodiments, the phenyl substituent at the 3 or 4 position is selected from CF3, Me, iPr, MeO, CN and CF3O. In a preferred embodiment, Ar2 is 3-methoxyphenyl. In another preferred embodiment, Ar2 is 3-methyl phenyl. In yet another preferred embodiment, Ar2 is 3-trifluoromethoxyphenyl. In still another embodiment, Ar2 is 3-triflouromethyl phenyl. In a further preferred embodiment, Ar2 is 4-isopropyl phenyl, and in still another preferred embodiment Ar2 is 3-cyanophenyl.
In suitable embodiments Ar2 is thiophene. In a preferred embodiment of the invention Ar2 is 2-thiophene.
In still another preferred embodiment Ar2 is 2-furan.
More preferred embodiments of the invention include:
(Z)-N-(1-(4-(4-Isopropylphenyl)phenyl)-1-(3-thienyl)prop-1-en-3-yl)sarcosine, (compound G(i));
(Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(3-thienyl)prop-1-en-3-yl)sarcosine, (compound G(ii));
(Z)-N-(1-(4-(2-Thienyl)phenyl)-1-(3-thienyl)prop-1-en-3-yl)sarcosine, (compound G(iii));
(Z)-N-(1-(4-(2-Furyl)phenyl)-1-(3-thienyl)prop-1-en-3-yl)sarcosine, (compound G(iv));
(Z)-N-(1-(4-(3-Methoxyphenyl)phenyl)-1-(3-thienyl)prop-1-en-3-yl)sarcosine, (compound G(v));
(Z)-N-(1-(4-(3-Methylphenyl)phenyl)-1-(3-thienyl)prop-1-en-3-yl)sarcosine, (compound G(vi));
(Z)-N-(1-(4-(3-(Trifluoromethoxy)phenyl)phenyl)-1-(3-thienyl)prop-1-en-3-yl)sarcosine, (compound G(vii));
(Z)-N-(1-(4-(3-Cyanophenyl)phenyl)-1-(3-thienyl)prop-1-en-3-yl)sarcosine, (compound G(viii));
(Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-thienyl)prop-1-en-3-yl)sarcosine, (compound G(ix));
(Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(3-(4-methylthienyl))prop-1-en-3-yl)sarcosine, (compound G(x));
(Z)-N-(1-(4-(3-(Trifluoromethyl)phenyl)phenyl)-1-(3-(4-methylthienyl))prop-1-en-3-yl)sarcosine, (compound G(xi));
(Z)-N-(1-(4-(3-Methoxyphenyl)phenyl)-1-(3-(4-methylthienyl))prop-1-en-3-yl)sarcosine, (compound G(xii));
(Z)-N-(1-(4-(3-Methylphenyl)phenyl)-1-(2-(3-methylthienyl))prop-1-en-3-yl)sarcosine, (compound G(xiii));
A most preferred embodiment of the invention is
(Z)-N-(1-(4-(2-Furyl)phenyl)-1-(3-thienyl)prop- 1-en-3-yl)sarcosine, (compound G(iv)).
Another suitable embodiment of the invention is the compound
(Z)-N-(1-(4-(3-Thienyl)phenyl)-1-(2-methylphenyl)prop-1-en-3-yl)sarcosine, (compound G(xiv)).
In another embodiment of the invention, the compound of Formula I is provided in labeled form, such as radiolabeled form (e.g. labeled by incorporation within its structure 3H or 14C or by conjugation to 125I). In a preferred aspect of the invention, such compounds, which bind preferentially to GlyT-1, can be used to identify GlyT-1 receptor ligands by techniques common in the art. This can be achieved by incubating the receptor or tissue in the presence of a ligand candidate and then incubating the resulting preparation with an equimolar amount of radiolabeled compound of the invention. GlyT-1 receptor ligands are thus revealed as those that significantly occupy the GlyT-1 site and prevent binding of the radiolabeled compound of the present invention. Alternatively, GlyT-1 receptor ligand candidates may be identified by first incubating a radiolabeled form of a compound of the invention then incubating the resulting preparation in the presence of the candidate ligand. A more potent GlyT-1 receptor ligand will, at equimolar concentration, displace the radiolabeled compound of the invention.
Base addition salts of the compounds of Formula I are most suitably formed from pharmaceutically acceptable acids. Also included within the scope of the invention are acid addition salts, solvates, and hydrates of compounds of the invention.
The conversion of a given compound salt to a desired compound salt is achieved by applying standard techniques, well known to one skilled in the art. 
Compounds of Formula 1 are readily prepared by the method shown in Scheme 1 above. Intermediate B was prepared by the palladium catalysed reaction of 4-bromoiodobenzene with propargyl alcohol. Compound B was converted to iodide C by treatment with sodium bis(2-methoxyethoxy)aluminum hydride(Red-Al) followed by iodine. A two step process consisting of conversion of alcohol to bromide followed by displacement with sarcosine led to the intermediate D. Intermediate D is a particularly useful intermediate as it allows the preparation of a number of derivatives where the aryl group can be oriented with complete stereochemical control. For example, common intermediate D was reacted with various boronic acids to yield products of the formula E.
The products of the formula E are also useful chemical intermediates. These products allow the preparation of numerous compounds with 4xe2x80x2-aryl groups (Ar2 groups). The products E are reacted with various boronic acids to yield a variety of products of the formula F which can be deprotected in the last step with formic acid to give the final compounds of type G.
Using the reactions described herein the following compounds of the invention have been made: 
The compounds of the invention may be administered orally, sublingually, rectally, nasally, vaginally, topically (including the use of a patch or other transdermal delivery device), by pulmonary route by use of an aerosol, or parenterally, including, for example, intramuscularly, subcutaneously, intraperitoneally, intraarterially, intravenously or intrathecally. Administration can be by means of a pump for periodic or continuous delivery. The compounds of the invention may be administered alone, or are combined with a pharmaceutically-acceptable carrier or excipient according to standard pharmaceutical practice. For the oral mode of administration, the compounds of the invention may be used in the form of tablets, capsules, lozenges, chewing gum, troches, powders, syrups, elixirs, aqueous solutions and suspensions, and the like. In the case of tablets, carriers that are used include lactose, sodium citrate and salts of phosphoric acid. Various disintegrants such as starch, and lubricating agents such as magnesium stearate and talc, are commonly used in tablets. For oral administration in capsule form, useful diluents are lactose and high molecular weight polyethylene glycols. If desired, certain sweetening and/or flavoring agents are added. For parenteral administration, sterile solutions of the compounds of the invention are usually prepared, and the pHs of the solutions are suitably adjusted and buffered. For intravenous use, the total concentration of solutes should be controlled to render the preparation isotonic. For ocular administration, ointments or droppable liquids may be delivered by ocular delivery systems known to the art such as applicators or eye droppers. Such compositions can include mucomimetics such as hyaluronic acid, chondroitin sulfate, hydroxypropyl methylcellulose or polyvinyl alcohol, preservatives such as sorbic acid, EDTA or benzylchromium chloride, and the usual quantities of diluents and/or carriers. For pulmonary administration, diluents and/or carriers will be selected to be appropriate to allow the formation of an aerosol.
Suppository forms of the compounds of the invention are useful for vaginal, urethral and rectal administrations. Such suppositories will generally be constructed of a mixture of substances that is solid at room temperature but melts at body temperature. The substances commonly used to create such vehicles include theobroma oil, glycerinated gelatin, hydrogenated vegetable oils, mixtures of polyethylene glycols of various molecular weight and fatty acid esters of polyethylene glycol. See, Remington""s Pharmaceutical Sciences, 16th Ed., Mack Publishing, Easton, Pa., 1980, pp. 1530-1533 for further discussion of suppository dosage forms. Analogous gels or creams can be used for vaginal, urethral and rectal administrations.
Numerous administration vehicles will be apparent to those of ordinary skill in the art, including without limitation slow release formulations, liposomal formulations and polymeric matrices.
Examples of pharmaceutically acceptable acid addition salts for use in the present invention include those derived from mineral acids, such as hydrochloric, hydrobromic, phosphoric, metaphosphoric, nitric and sulfuric acids, and organic acids, such as tartaric, acetic, citric, malic, lactic, fumaric, benzoic, glycolic, gluconic, succinic, p-toluenesulphonic and arylsulphonic acids, for example. Examples of pharmaceutically acceptable base addition salts for use in the present invention include those derived from non-toxic metals such as sodium or potassium, ammonium salts and organoamino salts such as triethylamine salts. Numerous appropriate such salts will be known to those of ordinary skill.
The physician or other health care professional can select the appropriate dose and treatment regimen based on the subject""s weight, age, and physical condition. Dosages will generally be selected to maintain a serum level of compounds of the invention between about 0.01 xcexcg/cc and about 1000 xcexcg/cc, preferably between about 0.1 xcexcg/cc and about 100 xcexcg/cc. For parenteral administration, an alternative measure of preferred amount is from about 0.001 mg/kg to about 10 mg/kg (alternatively, from about 0.01 mg/kg to about 10 mg/kg), more preferably from about 0.01 mg/kg to about 1 mg/kg (from about 0.1 mg/kg to about 1 mg/kg), will be administered. For oral administrations, an alternative measure of preferred administration amount is from about 0.001 mg/kg to about 10 mg/kg (from about 0.1 mg/kg to about 10 mg/kg), more preferably from about 0.01 mg/kg to about 1 mg/kg (from about 0.1 mg/kg to about 1 mg/kg). For administrations in suppository form, an alternative measure of preferred administration amount is from about 0.1 mg/kg to about 10 mg/kg, more preferably from about 0.1 mg/kg to about 1 mg/kg.
For use in assaying for activity in inhibiting glycine transport, eukaryotic cells, preferably QT-6 cells derived from quail fibroblasts, have been transfected to express one of the four known variants of human GlyT-1, namely GlyT-1a, GlyT-1b, GlyT-1c, or GlyT-1d, or human GlyT-2. The sequences of these GlyT-1 transporters are described in Kim et al., Molec. Pharm. 45: 608-617, 1994, excepting that the sequence encoding the extreme N-terminal of GlyT-1a was merely inferred from the corresponding rat-derived sequence. This N-terminal protein-encoding sequence has now been confirmed to correspond to that inferred by Kim et al. The sequence of GlyT-1d is described in U.S. Pat. No. 6,008,015, which is incorporated herein by reference in its entirety. The sequence of the human GlyT-2 is described in U.S. Pat. No. 5,919,653 which is incorporated herein by reference in its entirety. Suitable expression vectors include pRc/CMV (Invitrogen), Zap Express Vector (Stratagene Cloning Systems, LaJolla, Calif.; hereinafter xe2x80x9cStratagenexe2x80x9d), pBk/CMV or pBk-RSV vectors (Stratagene), Bluescript II SK +/xe2x88x92 Phagemid Vectors (Stratagene), LacSwitch (Stratagene), pMAM and pMAM neo (Clontech), among others. A suitable expression vector is capable of fostering expression of the included GlyT DNA in a suitable host cell, preferably a non-mammalian host cell, which can be eukaryotic, fungal, or prokaryotic. Such preferred host cells include amphibian, avian, fungal, insect, and reptilian cells.